In thyroid storm, which agent is used to rapidly control sympathetic symptoms?

• A. Propranolol
• B. Levothyroxine
• C. Methimazole
• D. Propylthiouracil

Answer: (A)

In thyroid storm, there is an exaggerated sympathetic (adrenergic) stimulation from excess thyroid hormone. The fastest way to blunt these symptoms is to block the adrenergic receptors themselves. A nonselective beta-blocker like propranolol does just that by blocking both beta-1 and beta-2 receptors, which reduces tachycardia, tremor, agitation, and hypertension. It also helps by lowering the conversion of T4 to the more active T3, offering an additional hormonal effect.

Levothyroxine would worsen the problem by adding thyroid hormone. Antithyroid drugs like methimazole or propylthiouracil reduce thyroid hormone production, but they take time to lower hormone levels and don’t provide the immediate relief of adrenergic symptoms. Propylthiouracil does have some effect on peripheral conversion, but the rapid control of symptoms comes from beta-blockade, making propranolol the best choice for this purpose.